Interpreting the position of a particle collision

[mrwolfy]

I am trying to track the position of particle collisions. I can get the value of the collision in U and V, but I am a bit confused as to how to interprert these coordinates to 3d space. the U value seems to relate to the x value of a locator that I have set up to position at these points, but V does not seem to correspond very well at all.

Any ideas?

Here is a youtube video.

There is the scene all set up: Scene.mb

float $colU = particleShape1.collisionU;
float $colV = particleShape1.collisionV;
int $time = `currentTime -q`;
if ($colU > 0) {
    particleShape1.lifespanPP=0;
    //print "HIT!";
    print ( "collisions in u:" + $colU + "collisions in v:" + $colV+"\n");
    //setAttr "loc.translateX" ($colU*10);
    setAttr "loc.translateZ" ($colV*10);
}
//print ("Collision: " + $colU + "\n");
//print ("Collision: " + $colV + "\n");

[nowayfra]

Your collision planes V-Value starts with 1 at the origin and ends with 0 at the point where your locator gets its maximum translateZ value. Simply correct your  expression to    

setAttr "loc.translateZ" ((1 - $colV) * 10);

or invert your collision planes scaleZ value.

[mrwolfy]

Nice Nawayfra, thanks! That worked of course.

[joojaa]

This leads to the question: Why would you use collisonU and collisionV if your purpose is to get the value of collisionPosition whre its directly stored in the form you need? Wouldnt just using collisionPosition be simpler then?